Method and Apparatus in a Wireless Communications System

ABSTRACT

A method in a user equipment for requesting that a base station schedule the user equipment for an uplink data transmission to the base station is provided. The user equipment comprises a buffer. Directly or indirectly responsive to receiving data into the buffer to be transmitted to the base station, the user equipment generates a scheduling request trigger. The scheduling request trigger is configured to trigger the sending of a scheduling request to the base station if the trigger is pending at the next scheduling request opportunity, and to remain pending until it is cancelled. The user equipment cancels the pending scheduling request trigger when the data is accounted for in a buffer status report, which reports the size of the buffer to the base station, or when the data is included directly in a scheduled uplink data transmission whichever occurs first.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) from the U.S.Provisional Patent Application with Ser. No. 61/175,668, filed on May 5,2009, and entitled “Connecting Cancellation of Pending SR with DataInclusion in BSR,” and also claims priority under 35 U.S.C. §365(c) fromthe International Patent Application with application numberPCT/SE2010/050063, filed on Jan. 25, 2010, and entitled “Method andArrangement in a Wireless Communications System.”

TECHNICAL FIELD

The present invention relates to a method and an apparatus in a userequipment. In particular, it relates to handling scheduling requesttriggers.

BACKGROUND

In a typical cellular radio system, also referred to as a wirelesscommunication system, User Equipments (UE)s communicate via a RadioAccess Network (RAN) to one or more core networks. The user equipmentsmay also be known as mobile terminals and/or wireless terminals. Inparticular, the user equipments may be mobile stations or user equipmentunits, such as mobile telephones (e.g., “cellular” telephones), andlaptops with wireless capability (e.g., mobile termination). Userequipments may therefore be portable, pocket, hand-held,computer-included, or car-mounted mobile devices which communicate voiceand/or data with the radio access network.

The radio access network covers a geographical area which is dividedinto cell areas, with each cell area being served by a base station,e.g., a Radio Base Station (RBS), which in some networks is also called“eNB”, “NodeB” or “B node” and which in this document is referred to asa base station. A cell is a geographical area where radio coverage isprovided by the radio base station equipment at a base station site. Thebase stations communicate over the air interface, operating on radiofrequencies, with user equipment units that are within range of the basestations.

In wireless communication systems, the radio UpLink (UL) is thetransmission path from the user equipment to a base station and theradio DownLink (DL) is the transmission path from a base station to theuser equipment. In Release 8, of the 3GPP Long Term Evolution (LTE)standard, the arrival of new UL data of higher priority than the alreadyexisting data, or of any priority when there is no previous data, to theUE buffer triggers a so-called Regular Buffer Status Report (BSR). Thereare, of course, side conditions to this. For example, new UL data onlytriggers a BSR if it is data for a logical channel belonging to aLogical Channel Group (LCG). Further, the “arrival of new UL data” isdefined as when UL data becomes available for transmission in a RadioLink Controller (RLC) entity, or in the Packet Data Convergence Protocol(PDCP) entity. The PDCP is an upper layer of the RLC entity

However, notwithstanding these side conditions, the arrival of new ULdata generally triggers a regular BSR. The regular BSR, in turn,triggers the generation of a Scheduling Request (SR) trigger. The SRtrigger then triggers an SR to be conveyed to the base station, therebyinforming the base station that the user equipment has new data that itwould like to transmit. The SR is transmitted to the base station eitheron (1) the user equipment's preallocated scheduling request resource ona Physical Uplink Control Channel (PUCCH), in which case the SR is knownas dedicated SR (D-SR) since it is transmitted on a resource dedicatedto the user equipment, or (2) on the Physical Random Access Channel(PRACH), in which case the SR is known as a random access SR (RA-SR). Inboth cases, there is a fixed periodicity associated with theopportunities to transmit an SR. This means that, in order to transmitan SR, the user equipment has to wait until such an opportunity isavailable.

When the base station receives a D-SR, the base station typically issuesan UL grant. When the user equipment transmits on that grant, it willtransmit a MAC Packet Data Unit (PDU) that includes a BSR in the shapeof a so-called BSR Medium Access Control (MAC) control element,describing the size of its buffers. The BSR is mandated to reflect thebuffer status after the MAC PDU, including the BSR MAC control element,is built. A BSR is always included if a BSR trigger is pending in theuser equipment at the time of building the MAC PDU, unless all data canfit in the MAC PDU but there is not room enough for a BSR in addition tothe data.

Once the size of the user equipment buffer has been reported to the basestation, there is no need for the user equipment to send additional SRsas the base station now knows how much data the user equipment has totransmit. The SR trigger can hence be cancelled in the user equipment,so that the user equipment will not send any D-SR at the next D-SRopportunity.

Please note that in the description below, the following terminologywill be used:

The term “arrival of new data” is used to indicate arrival of new ULdata in the user equipment buffer, with all side conditions fortriggering a Regular BSR satisfied.

The term “reception of grant” is used to indicate the reception of aPhysical Downlink Control Channel (PDCCH) grant for Uplink SharedChannel (UL-SCH) resources for a new transmission.

The term “transmission of data” is used to indicate transmission of ULdata on UL-SCH resources that have been made available for a newtransmission.

The term “SR” and “scheduling request” is used to indicate signalling ofD-SR on the PUCCH.

The term “SR trigger” and “scheduling request trigger” is used toindicate a pending SR.

When expressions such as “buffer status report accounts for first data”are used, it means that the buffer status report reflects whatever isleft of the first data after the transmission in which the buffer statusreport is included has been received.

An SR is considered pending until cancelled, i.e. an SR trigger thattriggers the transmission of an SR, is considered pending untilcancelled. It was first agree upon, in a prior version of the LTEstandard, that an SR would be cancelled in the first possibleTransmission Time Interval (TTI), also known as subframe, when UL-SCHresources for a new transmission are granted. However, some argued thatit was unclear exactly when UL-SCH resources for a new transmission aregranted, whether it be when a PDCCH grant is received or in the TTI whenthe UL-SCH resources are actually available. It was subsequently agreedupon that all pending SRs should be cancelled in the TTI when UL-SCHresources are actually available for a new transmission.

SUMMARY

Embodiments of the present invention improve the performance of awireless communications network.

One embodiment of the present invention, for example, comprises a methodin a user equipment for requesting that a base station schedule the userequipment for an uplink data transmission to the base station. The userequipment comprises a buffer. The method includes receiving data intothe buffer that is to be transmitted to the base station via a scheduleduplink data transmission. The method then includes sending a schedulingrequest to the base station when a next scheduling request opportunityoccurs, if and only if the buffer comprises data that has neither beenaccounted for in a buffer status report, which reports the size of thebuffer to the base station, or included directly in a scheduled uplinkdata transmission

In another embodiment, the user equipment generates a scheduling requesttrigger after receiving data into the buffer to be transmitted to thebase station. The scheduling request trigger is triggered directly orindirectly by the arrived data; that is, the user equipment generatesthe scheduling request trigger directly, or indirectly, responsive tothe arrival of such data. The scheduling request trigger is configuredto trigger the sending of a scheduling request to the base station ifthe trigger is pending at the next scheduling request opportunity. Oncegenerated, the scheduling request trigger remains pending until it iscancelled by the user equipment. The user equipment cancels the pendingscheduling request trigger when the data is accounted for in a bufferstatus report, or when that data is included directly in a scheduleduplink data transmission, whichever occurs first.

According to yet another embodiment, the user equipment tracks what datain the buffer has been accounted for in a buffer status report and whatdata in the buffer has been included directly in a scheduled uplink datatransmission. The user equipment also tracks what data has not beenaccounted for in a buffer status report or included directly in ascheduled uplink data transmission.

Various embodiments of the present invention likewise include a userequipment configured with one or more circuits for performing the abovemethods.

Regardless, each embodiment of the present invention advantageouslysends a scheduling request only when necessary. For example, manyembodiments cancel the sending of a pending scheduling request when ithas served its purpose. This is only guaranteed if the schedulingrequest is cancelled when the data that triggered it is accounted for ina buffer status, or the data that triggered it is included in ascheduled transmission. Thereby the performance in the wirelesscommunications network improves by making sure no scheduling requestsare sent unnecessarily and no scheduling requests are cancellederroneously. Unnecessarily sent scheduling requests lead to increasedinterference and potentially to unnecessary grants for Uplink SharedChannel resources being sent by the base station, and erroneouslycancelled scheduling requests can lead to the user equipment not beingable to transmit data in its buffer.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in more detail with reference to attacheddrawings illustrating exemplary embodiments of the invention and inwhich:

FIG. 1 is a schematic diagram illustrating an analysis of the problemaddressed by various embodiments of the present invention.

FIG. 2 is a schematic diagram illustrating an analysis of the problemaddressed by various embodiments of the present invention.

FIG. 3 is a schematic diagram illustrating an analysis of the problemaddressed by various embodiments of the present invention.

FIG. 4 is a schematic block diagram illustrating a wirelesscommunication network according to one embodiment of the presentinvention.

FIG. 5 is a flowchart depicting a method according to one embodiment ofthe present invention.

FIG. 6 is a schematic diagram illustrating an analysis of variousembodiments of the present invention.

FIG. 7 is a schematic diagram illustrating an analysis of variousembodiments of the present invention.

FIG. 8 is a schematic diagram illustrating an analysis of variousembodiments of the present invention.

FIG. 9 is a schematic block diagram illustrating a user equipmentaccording to one embodiment of the present invention.

FIG. 10 is a schematic block diagram illustrating a user equipmentaccording to one embodiment of the present invention.

DETAILED DESCRIPTION

As mentioned above, the latest version of the LTE standard specifiesthat all pending SRs shall be canceled in the TTI when UL-SCH resourcesare actually available for a new transmission. FIG. 1 illustrates ananalysis of this alternative in the case that new, second data arrivesto the user equipment buffer before a grant for the first data isreceived. That is, assume that first data has arrived to the userequipment buffer. This first data has triggered a buffer status report.This first data has also directly or indirectly triggered a firstscheduling request trigger, for sending a scheduling request at the nextscheduling request opportunity. The scheduling request opportunity hasoccurred and a first scheduling request has been transmitted to the basestation. The first scheduling request trigger is still pending. It willbe cancelled upon transmission of UL data; that is, in the TTI whenUL-SCH resources are actually available for transmitting that UL data.

Looking at a time line, there are then two different cases that appear,case a) and case b) illustrated in FIG. 1. In case a), the userequipment has a scheduling request opportunity between receiving the ULgrant and transmitting the data. In case b) the user equipment has noscheduling request opportunity between receiving the UL grant andtransmitting the data; the next SR opportunity occurs after thetransmission of the data.

For case a) assume the following steps:

Step 100. New second data arrives in the user equipment buffer. Thissecond data triggers a buffer status report trigger. This second data,directly or indirectly via the buffer status report trigger, alsotriggers a second scheduling request trigger to send a schedulingrequest for the second data at the next opportunity.

Step 110. As a response to the first scheduling request sent to the basestation, the user equipment receives from the base station, an UL grantfor transmission.

Step 115. The first and second scheduling request triggers are pending,implying that the user equipment will send a scheduling request to thebase station at the next scheduling request opportunity. At this pointin time a scheduling request opportunity occurs, i.e., this schedulingrequest opportunity occurs between receiving the UL grant andtransmitting the data according to case a). Therefore the user equipmentagain sends a scheduling request to the base station although a granthas already been received. This is unnecessary to send and is confusingfor the base station to receive. This is a disadvantage.

Step 120. In this step the user equipment transmits to the base station.It cannot be known for sure if the user equipment transmission includesdata from the first or second data since the grant is just a grant ofresources and the user equipment makes the decision of which data totransmit. The second data may be of higher priority than the first data,in which case parts of second data will be sent. However, a bufferstatus report is also included in the transmission to the base station,unless all data can fit in the transmission but not a buffer statusreport. If included, the buffer status report accounts for whatever isleft of the first data and also for the second data after the scheduledtransmission has been made. Since the rule in this example is to cancelSR at transmission of UL data, the user equipment cancels both pendingSR triggers at this point in time. However, the base station does notknow how to interpret the second scheduling request 115. Based on thesecond scheduling request, it may send a new grant thinking there ismore data that has not been accounted for in the transmission (120). Ifthe buffer status report sent in the transmission (120) reflects emptybuffers, such a new grant will only be filled by transmitting paddingbits, meaning that both the grant and the padding transmission wereunnecessary, taking resources that could have been used for other userequipments.

For case b) there are fewer problems. Assume the following steps:

Step 100. New second data arrives in the user equipment buffer. Thissecond data triggers a buffer status report trigger. This second data,directly or indirectly via the buffer status report trigger, alsotriggers a second scheduling request trigger to send a schedulingrequest for the second data at the next opportunity.

Step 110. As a response to the first scheduling request sent to the basestation, the user equipment receives from the base station, an UL grantfor transmission.

Step 120. The user equipment transmits to the base station. Again, itcannot be known for sure if the user equipment transmission includesdata from the first or second data. A buffer status report is includedin the transmission to the base station, which buffer status reportaccounts for the first data and also for the second data since thesecond data arrived before the grant. Since the rule in this example isto cancel scheduling request at transmission of UL data, the userequipment cancels both pending scheduling request triggers at this pointin time. This is good since no further scheduling requests need to besent.

Step 125. A scheduling request opportunity occurs at this point in time,i.e. after the transmission of the data according to case b). The userequipment had no scheduling request opportunity between receiving the ULgrant and transmitting the data as in case a). The scheduling requesttriggers are canceled and therefore not pending any more. This meansthat the user equipment will not again send a scheduling request to thebase station at this next scheduling request opportunity. It is OK thatthe scheduling request was cancelled at the transmission. Since thesecond data arrived before the grant, it is assured that the second datais accounted for in the buffer status report or fully included in thetransmission. That is good and safe.

In case a), the scheduling request trigger has not yet been cancelledwhen the scheduling request opportunity occurs. Hence, a new schedulingrequest is sent, although the user equipment has already received agrant in response to its previous scheduling request. There is no needfor the second scheduling request in this case, but the user equipmentis mandated by the specification to send it. This is a waste of userequipment energy and of radio resources, since the scheduling requestcreates unnecessary interference on the Physical Uplink Control Channel(PUCCH). Additionally, it is not clear what the base station should doin response to the unnecessary scheduling request. Note that the sameprocedure, with an extra unnecessary scheduling request and its unwantedconsequences, would happen in case a) even if the user equipmentreceived the first data but no second data.

However, there is an even more complicated case with worse problems inthe following example related to FIGS. 2 and 3, where the user equipmentgets new data to its buffer after a grant corresponding to the firstscheduling request is received. This new data triggers a schedulingrequest trigger. Looking at a time line, there are then two differentcases that appear, case a) illustrated in FIG. 2 and case b) illustratedin FIG. 3. In this example, as in the example in case a) relating toFIG. 1, the user equipment has a scheduling request opportunity betweenreceiving the UL grant and transmitting the data. In case b) the userequipment has no scheduling request opportunity between receiving the ULgrant and transmitting the data; the next scheduling request opportunityoccurs after the transmission of the data.

In case a) and in case b) there are two respective alternatives,alternative I and alternative II. FIG. 2 depicts case a) alternative Iand case a) alternative II, and FIG. 3 depicts case b) alternative I andcase b) alternative II.

Hence, FIG. 2 illustrates an analysis of the alternative to a cancel SRat transmission of UL data, when new data arrives between reception ofgrant and transmission of data corresponding to the grant for case a),wherein the user equipment has an SR opportunity between receiving theUL grant and transmitting the data. For example, assume that first datahas arrived to the user equipment buffer. This first data has triggereda buffer status report trigger. This first data has also, directly orindirectly via the buffer status report trigger, triggered a firstscheduling request trigger, for sending a scheduling request at the nextscheduling request opportunity. The SR opportunity has occurred and thefirst scheduling request has been transmitted to the base station. Thefirst scheduling request trigger has not yet been cancelled, however, istherefore still pending. It will be cancelled upon transmission of ULdata.

For case a-I) assume the following steps:

Step 200 case a-I). As a response to the SR sent to the base station,the user equipment receives from the base station an UL grant fortransmission.

Step 210 case a-I). During a time period the user equipment builds apacket data unit, such as a MAC PDU, for parts or all of the first datato be transmitted in, and includes a buffer status report in the packetdata unit (unless all data can fit in but not a buffer status report).This packet data unit shall be sent to the base station at thetransmission later on. The buffer status report accounts only for thefirst data.

Step 220 case a-I). New second data arrives in the user equipmentbuffer. This second data triggers a buffer status report. This seconddata further, directly or indirectly via the buffer status reporttrigger, triggers a second scheduling request trigger to send ascheduling request at the next opportunity. The second schedulingrequest trigger is pending in addition to the first scheduling requesttrigger, triggered by the first and the second data, respectively.

Step 240 case a-I). At this point in time a scheduling requestopportunity occurs, i.e., this scheduling request opportunity occursbetween receiving the UL grant and transmitting the data according tocase a). Therefore the user equipment sends a second scheduling requestto the base station, since the scheduling request has not yet beencancelled. This is necessary as the user equipment has already built thepacket data unit including parts or all of the first data to be sent,before the second data became available in the user equipment buffer.The second data is thereby not accounted for in the buffer status reportwhich will be sent at the transmission.

Step 250 case a-I). The user equipment transmits the packet data unitincluding the buffer status report, which buffer status report wastriggered by the first data (mentioned above) and which buffer statusreport accounts for the first data but not the second data. Since therule in this example is to cancel a scheduling request at transmissionof UL data, the user equipment cancels both pending scheduling requesttriggers at this point in time. At this point, it is difficult for thebase station to know how to interpret the second scheduling requestsent; it does not know if the second scheduling request corresponds tosecond data, or if it corresponds to the first data, whose schedulingrequest trigger had not yet been cancelled. If the base station does notsend a grant, it risks leaving the user equipment with data in itsbuffer, unable to transmit, and if it does send a new grant, it risksthat this grant was unnecessary and the corresponding transmission willonly be padding. Additionally, if the second scheduling request is notheard by the base station, e.g. because of excessive interference onPUCCH or PUCCH coverage problems, the scheduling request triggers arenow cancelled and no new scheduling request will be sent even if no newgrant is received for the second data. This means that the userequipment cannot get a grant from the base station to transmit itssecond data, which will remain in the user equipment since the basestation does not know of its existence.

For case a-II) assume the following steps:

Step 200 case a-II). As a response to the first scheduling request sentto the base station, the user equipment receives from the base station,an UL grant for transmission.

Step 220 case a-II). New second data arrives in the user equipmentbuffer. This second data triggers a buffer status report trigger. Thissecond data further, directly or indirectly via the buffer status reporttrigger, triggers a second scheduling request trigger, to send ascheduling request at the next opportunity. In case a-II), the seconddata arrives before building the packet data unit, whereas in case a-Ithe second data arrived after building the packet data unit.

Step 230 case a-II). During a time period the user equipment builds apacket data unit, such as a MAC PDU, for data to be transmitted in,which data is built in the packet data unit depending on the priority ofthe data in user equipment buffer. The user equipment includes a bufferstatus report in the packet data unit (unless all data can fit in butnot a buffer status report). This packet data unit shall be sent to thebase station at the transmission later on. The buffer status reportaccounts for both the first data and the second data.

Step 240 case a-II). The first and second scheduling request triggersare pending. At this point in time a scheduling request opportunityoccurs, i.e., this scheduling request opportunity occurs betweenreceiving the UL grant and transmitting the data according to case a).Therefore the user equipment again sends a scheduling request to thebase station, since both scheduling request triggers are not yetcancelled. Just as in FIG. 1 a, this is unnecessary, since both firstand second data will be included in the buffer status report sent onalready allocated resources.

Step 250 case a-II). The user equipment transmits data and the bufferstatus report in the built packet data unit, which buffer status reportaccounts for the first data and the second data. Since the rule in thisexample is to cancel scheduling request at transmission of UL data, theuser equipment cancels both pending scheduling request triggers at thispoint in time.

In both case a-I and case a-II, an extra scheduling request is sent.Moreover, when receiving the extra scheduling request, the base stationonly knows that it has received two scheduling requests and thereforecannot distinguish between case a-I and case a-II, i.e. the base stationcannot determine whether the same data was behind both schedulingrequests, or if additional data was received for the second schedulingrequest. Correspondingly, the base station does not know if the bufferstatus report it received actually reflects the user equipment buffersizes, as new data could have arrived after the buffer status report wasbuilt. The base station hence has to guess, and depending on its guessit risks either wasting a grant or losing track of the new data (since,because the new data has not been reported, the base station would havean inaccurate buffer size estimation).

FIG. 3 illustrates an analysis of the alternative to cancel a schedulingrequest at transmission of UL data, when new data arrives betweenreception of grant and transmission of data corresponding to the grantfor case b), wherein the user equipment has no scheduling requestopportunity between receiving the UL grant and transmitting the data;the next scheduling request opportunity occurs after the transmission ofthe data. Assume, for instance, that first data has arrived to the userequipment buffer. This first data has triggered a buffer status reporttrigger. This first data also, directly or indirectly via the bufferstatus report trigger, has triggered a first scheduling request trigger,for sending a scheduling request at the next scheduling requestopportunity. The scheduling request opportunity has occurred and thefirst scheduling request has therefore been transmitted to the basestation. The first scheduling request trigger has not yet beencancelled, and is therefore still pending. It will be cancelled upontransmission of UL data.

For case b-I) assume the following steps:

Step 300 case b-I). As a response to the scheduling request sent to thebase station, the user equipment receives from the base station an ULgrant for transmission.

Step 310 case b-I). During a time period the user equipment builds apacket data unit, such as a MAC PDU, for parts or all of the first datato be transmitted in, and includes a buffer status report in the packetdata unit (unless all data can fit in but not a buffer status report).The packet data unit shall be sent to the base station at thetransmission later on. The buffer status report accounts only for thefirst data.

Step 320 case b-I). New second data arrives in the user equipmentbuffer. This second data triggers a buffer status report. This seconddata further, directly or indirectly via the buffer status reporttrigger, triggers a second scheduling request trigger to send ascheduling request at the next opportunity.

Step 340 case b-I). The user equipment transmits the first data built inthe packet data unit and includes the buffer status report in the packetdata unit, which buffer status report was triggered by the first dataand which buffer status report accounts for the first data but not thesecond data. Since the rule in this example is to cancel a schedulingrequest at transmission of UL data, the user equipment cancels bothpending scheduling request triggers at this point in time. This meansthat there is no longer any pending scheduling request triggers toindicate that there is second data in the user buffer, even though noscheduling request for the second data has been transmitted to the basestation yet, since no scheduling request opportunity has appeared atthis point in time. In this case, the scheduling request needed for thesecond data will be lost!

Step 350 case b-I). At this point in time a scheduling requestopportunity occurs i.e. after the transmission of the data according tocase b). No scheduling request trigger is pending since it was cancelledin step 340. So as mentioned above, in this case, the SR for the seconddata will be lost. This is not good.

For case b-II) assume the following steps:

Step 300 case b-II). As a response to the scheduling request sent to thebase station, the user equipment receives from the base station an ULgrant for transmission.

Step 320 case b-II). New second data arrives in the user equipmentbuffer. This second data triggers a buffer status report trigger. Thissecond data further, directly or indirectly, triggers a secondscheduling request trigger, to send a scheduling request at the nextopportunity. Thus in case b-II), the second data arrives before buildingthe packet data unit, whereas in case b-I) the second data arrived afterbuilding the packet data unit.

Step 330 case b-II). During a time period the user equipment builds apacket data unit, such as a MAC PDU, for data to be transmitted in,which data is built in the packet data unit depending on the priority ofthe data in the user equipment buffer. The user equipment includes abuffer status report in the packet data unit (unless all data can fit inbut not a buffer status report). This packet data unit shall be sent tothe base station at the transmission later on. The buffer status reportaccounts for both the first data and the second data.

Step 340 case b-II). The user equipment transmits the data and thebuffer status report in the packet data unit, which buffer status reportaccounts for the first data and the second data. Since the rule in thisexample is to cancel SR at transmission of UL data, the user equipmentcancels the pending SR trigger at this point in time.

Step 350 case b-II). At this point in time, an SR opportunity occursi.e. after the transmission of the data according to case b). No SRtrigger is pending since it was cancelled in step 340. This is good inthis case, since first and second data are already transmitted oraccounted for in the BSR.

As can be seen, case b-II) works well but case b-I) does not. In bothcases, the triggered second scheduling request trigger is never sent asit is cancelled when the first data is transmitted. However, if thesecond data is not included in the buffer status report sent as in caseb-I), the base station will not know about this data. Two things maysave the situation: (1) the user equipment receiving a grant for otherdata, not in response to the scheduling request never sent, since thetransmission on that grant will include a buffer status report, or (2) anew SR being triggered by the arrival of yet new data.

Unless one of these occurs, the user equipment has no means of sending anew scheduling request until the fallback mechanism known as “retransmitbuffer status report timer” or “retx-BSR-Timer” expires, triggering ascheduling request. However, this timer has a minimum value of 320 mswhich adds considerable delay.

Therefore it is an object of the invention to provide a mechanism in auser equipment that improves the performance in the wirelesscommunications network.

Referring now to one embodiment of the present invention, FIG. 4 depictsa wireless communications system 100. The wireless communications system100 is a packet-based communications system, which may be an LTEcommunications system, Worldwide Interoperability for Microwave Access(WiMax) system, or any other wireless communications system handlingscheduling requests for uplink scheduling.

The wireless communications system 100 comprises a base station 110serving a cell 115. The base station 110 is a radio base station such asan eNB, a Radio Base Station (RBS) or any other network unit capable ofcommunicating over a radio carrier with user equipments being present inthe cell.

A user equipment 120 being present within the cell 115, is served by thebase station 110, and is therefore capable of transmitting data packetunits such as MAC PDUs to the base station 110 over a radio channel 125.The user equipment 120 may be a terminal, e.g. a mobile terminal or awireless terminal, a mobile phone, a computer such as e.g. a laptop,Personal Digital Assistants (PDA), or any other radio network unitscapable to communicate with a base station over an air interface. Theair interface may e.g. be an E-UTRA air interface used in LTE.

The user equipment 120 comprises a buffer, to which buffer new uplinkdata arrives that is to be transmitted to the base station 110. The datamay be voice data, video data, photo data, text data or any other kindof data that a user may want to transmit. The arrival of new UL data ofhigher priority than the already existing data, or of any priority whenthere is no previous data, to the user equipment buffer triggers abuffer status report. The arrived new data further directly orindirectly triggers a scheduling request trigger to be pending. Theindirectly triggering may be performed such that the arrived datatriggers a buffer status report which in turn triggers the schedulingrequest trigger. The scheduling request trigger will trigger ascheduling request to be sent to the base station 110 at a nextscheduling request opportunity. The “scheduling request trigger” mayalso be referred to as “a pending scheduling request”. As mentionedabove there is a fixed periodicity associated with the opportunities totransmit scheduling requests to the base station 110, so the userequipment 120 has to wait until such an opportunity is available. Thebase station 110 receiving the scheduling request is in that wayinformed that the user equipment 120 has new data that it would like totransmit. A scheduling request trigger is pending or not pending. Ascheduling request is typically not associated with any specific arriveddata and a scheduling request trigger does not need to be associatedwith any data, although it is implicitly associated with the data thattriggered it. But if further data, here called second data, arrives tothe user equipment buffer, thereby triggering a scheduling requesttrigger, a further scheduling request is triggered, even if a schedulingrequest trigger is already triggered.

As a response to a scheduling request, the base station 110 typicallysends an uplink grant to the user equipment 120. The grant is specificto a user equipment, but is not associated with any specific arriveddata in that user equipment. Priorities set by the eNB and signalled tothe user equipment 120 decides which particular data shall betransmitted on the resources that the user equipment 120 has beenallocated.

To make the handling of the scheduling procedure more reliable, whichwill improve the performance in the wireless communications network, apending scheduling request trigger is cancelled in accordance with oneembodiment of the present invention as follows:

In a first embodiment, the pending scheduling request is cancelled whenthe data that triggered the scheduling request is accounted for in abuffer status report to be included in a scheduled data transmission tobe transmitted to the base station 110, or when the data that triggeredthe scheduling request is included in a scheduled data transmission tobe transmitted to the base station, whichever occurs first. In thislatter case, the scheduled data need not be transmitted, just includedin the packet data unit that a bit later will be transmitted.

Alternatively, in a second embodiment, the pending scheduling request iscancelled at any time by the user equipment, but the user equipment 120keeps track of what data has been accounted for in the buffer statusreport to be included in a scheduled data transmission and what data hasnot been accounted for. In this case, when a next scheduling requestopportunity appears, the user equipment 120 sends a scheduling requestif and only if the buffer comprises data that has not yet been accountedfor in a buffer status report. This is equivalent to having a pendingscheduling request in the first embodiment, but does not necessarilyhave to be called “having a pending scheduling request”. The consequencewill however be the same: at the next scheduling request opportunity,the user equipment 120 will send a scheduling request if there is datanot yet included in a buffer status report, and that data has not yetbeen sent.

A method in the user equipment 120 for handling a scheduling requesttrigger, according to some embodiments, will now be described withreference to the flowchart depicted in FIG. 5. As mentioned above, theuser equipment 120 comprising a buffer.

The method comprises the following steps, which steps may as well becarried out in another suitable order than described below:

Step 501

The buffer in the user equipment 120 receives data to be transmitted toa base station 110.

Step 502

This step is optional, according to some embodiments, the user equipment120 generates a buffer status report trigger. The buffer status reporttrigger is triggered by the arrived data.

Step 503

The user equipment 120 generates a scheduling request trigger, whichscheduling request trigger is pending until it is cancelled, and whichgeneration is triggered directly or indirectly by the arrived data. Insome embodiments where this step is performed indirectly, the generationis triggered by the generation of the buffer status report trigger,which in turn was triggered by the arrived data.

Step 504

According to a first embodiment, the user equipment 120 cancels thepending scheduling request when the data that triggered the schedulingrequest is accounted for in a buffer status report to be included in ascheduled data transmission to be transmitted to the base station 110,or the user equipment 120 cancels the pending scheduling request whenthe data that triggered the scheduling request is included in ascheduled data transmission to be transmitted to the base station,whichever occurs first. The pending scheduling request trigger may hencebe cancelled at the same time instance during which the MAC PDUincluding a buffer status report MAC control element is built.

When a packet data unit such as a MAC PDU is built, it includes a bufferstatus report such as a BSR MAC control element. The buffer statusreport accounts for data remaining in the user equipment buffer afterthe of building the packet data unit. Such a buffer status report isincluded if a buffer status report trigger is pending at the time thatthe MAC PDU is built, and all data cannot fit in the MAC PDU.

The user equipment 120 may cancel the pending scheduling request whenthe data that triggered the scheduling request is included in the bufferstatus report represented by a BSR MAC control element or when all datathat triggered the scheduling request has been included in a MAC PDU fortransmission. In the context of the LTE standards, such a method ofoperation can be understood as the user equipment 120 canceling apending scheduling request when the buffer status report that triggeredthe scheduling request is canceled. Here, “when” does not necessarilyconnote a coincidence in time, and can be understood as the pendingscheduling request being canceled upon cancellation of the pendingbuffer status report that triggered the pending scheduling request. Inother words, in at least one embodiment, a pending scheduling requesttrigger is canceled, e.g. along with canceling the corresponding bufferstatus report trigger, if a currently scheduled data transmission willinclude all of the new data that caused the corresponding buffer statusreport trigger to be generated, or if a buffer status report to beincluded in the next currently scheduled data transmission—which mayhave been generated because of one or more other pending buffer statusreport triggers—will account for the new data.

Step 505

According to a second embodiment, as an alternative to step 504, theuser equipment 120 cancels the pending scheduling request at any time,but the user equipment 120 keeps track of what data has been accountedfor in the buffer status report to be included in a scheduled datatransmission and what data has not been accounted for, and according tosome embodiments, nor been included in a scheduled data transmission.

Step 506

According to the second embodiment, when a next scheduling requestopportunity appears, the user equipment 120 sends a scheduling requestif and only if the buffer comprises data that has not yet been accountedfor in the buffer status report.

In this alternative embodiment, the user equipment 120 may internallycancel its pending scheduling request trigger whenever it wants, beforeor after the point in time in which the user equipment would havecancelled it according to the first embodiment in step 504, while stillfulfilling the behaviour that can be tested by the 3GPP. This is, asmentioned above, performed by the user equipment 120 keeping track ofdata that has not yet been included in a buffer status report, andaccording to some embodiments, nor been included in a scheduled UL datatransmission. This is equivalent to having a pending scheduling requestin the first embodiment, but does not necessarily have to be called“having a pending scheduling request”. The consequence will however bethe same, at the next scheduling request opportunity, the user equipment120 will send a scheduling request if there is data not yet included ina buffer status report, and that data has not yet been sent.

Further, in some embodiments as mentioned above, the buffer statusreport trigger may be generated in response to new data incoming to anuplink transmit buffer, and a scheduling request trigger may begenerated corresponding to the buffer status report trigger. Thus,receiving new data into the uplink transmit buffer causes a new bufferstatus report trigger to be generated, which causes a new schedulingrequest trigger.

In one or more embodiments taught herein, advantageous handling andcancelling of pending buffer status report triggers and correspondingpending scheduling request triggers prevents uplink data from becomingstuck in the user equipment 120, and/or prevents or at least reducesunnecessary scheduling request transmissions and resultant unnecessaryuplink resource grants.

Those skilled in the art will also appreciate that buffer status reporttriggers and corresponding scheduling request triggers may beimplemented as flags or other logical indicators, which may be set orotherwise created to indicate the pending status, and cleared orotherwise deleted for cancellation.

FIG. 6 illustrates an analysis of the present invention according to thefirst embodiment, when new second data arrives to the user equipmentbuffer before a grant for the first data is received, i.e., the firstembodiment comprises cancelling the scheduling request trigger when thedata that triggered the scheduling request is accounted for in a bufferstatus report to be included in a scheduled data transmission to betransmitted to the base station 110, or cancelling the pendingscheduling request when the data that triggered the scheduling requestis included in a scheduled data transmission to be transmitted to thebase station, whichever occurs first. Assume again that first data hasarrived to the user equipment buffer, which corresponds to step 501 inFIG. 5. This first data has triggered a buffer status report, whichcorresponds to step 502 in FIG. 5. This first data has also directly orindirectly triggered a first scheduling request trigger, for sending ascheduling request at the next scheduling request opportunity, whichcorresponds to step 503 in FIG. 5. The scheduling request opportunityhas occurred and the first scheduling request has been transmitted tothe base station 110. The first scheduling request trigger is stillpending. Looking at a time line, there are then two different cases thatappears, case a) and b) illustrated in FIG. 6. In case a), the userequipment 120 has a scheduling request opportunity between receiving theUL grant and transmitting the data. In case b) the user equipment 120has no scheduling request opportunity between receiving the UL grant andtransmitting the data; the next scheduling request opportunity occursafter the transmission of the data.

For case a) assume the following steps:

Step 600. New second data arrives in the user equipment buffer. Thissecond data triggers a buffer status report. This second data directlyor indirectly via the buffer status report trigger, triggers a secondscheduling request trigger to send a scheduling request at the nextopportunity.

Step 610. As a response to the first scheduling request sent to the basestation 110, the user equipment 120 receives an UL grant fortransmission from the base station 110.

Step 612. During a time period the user equipment 120 builds a packetdata unit, such as a MAC PDU, for parts or all of the first and seconddata to be transmitted in, and includes a buffer status report in thepacket data unit (unless all data can fit in but not a buffer statusreport). The packet data unit shall be sent to the base station 110 atthe transmission later on. According to this embodiment, all pendingscheduling request triggers are canceled at this point in time, and alsoall pending buffer status report triggers.

Step 615. The first and second scheduling request triggers are notpending, implying that the user equipment 120 will not send a schedulingrequest to the base station 110 at the next scheduling requestopportunity. Thus, at this point in time when a scheduling requestopportunity occurs, no scheduling request is sent. This is good, sinceall data has been accounted for either in a buffer status report or inthe scheduled transmission.

Step 620. The user equipment 120 transmits the built packet data unit tothe base station 110.

For case b) assume the following steps:

Step 600. New second data arrives in the user equipment buffer. Thissecond data triggers a buffer status report trigger. This second datadirectly or indirectly via the buffer status report triggers ascheduling request trigger to send a scheduling request at the nextopportunity. This step is the same as for case a).

Step 610. As a response to the first scheduling request sent to the basestation 110, the user equipment 120 receives from the base station, anUL grant for transmission. This step is also the same as for case a).

Step 612. During a time period the user equipment 120 builds a packetdata unit, such as a MAC PDU, for parts or all of the first and seconddata to be transmitted in, and includes a buffer status report in thepacket data unit (unless all data can fit in but not a buffer statusreport). The packet data unit shall be sent to the base station 110 atthe transmission later on. According to this embodiment, all pendingscheduling request triggers are canceled at this point in time, and alsoall pending buffer status report triggers.

Step 620. The user equipment 120 transmits the built packet data unit tothe base station 110. Again, it cannot be known for sure if the userequipment 120 transmits according to first or second data. A bufferstatus report is included in the transmission to the base station 110,which buffer status report accounts for the first and also for thesecond data since the second data arrived before the grant. The rule inthis example is to cancel the scheduling request trigger when the datathat triggered the scheduling request is accounted for in a bufferstatus report to be included in a scheduled data transmission to betransmitted to the base station 110, or the user equipment 120 cancelsthe pending scheduling request when the data that triggered thescheduling request is included in a scheduled data transmission to betransmitted to the base station, whichever occurs first. Since thisbuffer status report and the data packet unit including first and seconddata was built before this point in time of sending, i.e. before step620, the user equipment 120 has cancelled the pending scheduling requesttriggers. This is good, since there is no reason to send an additionalscheduling request at the next scheduling request opportunity.

Step 625. A scheduling request opportunity occurs at this point in time,i.e. after the transmission of the data according to case b). The userequipment 120 had no scheduling request opportunity between receivingthe UL grant and transmitting the data as in case a). The schedulingrequest trigger is already canceled and therefore not pending any more.This means that the user equipment 120 will not again send a schedulingrequest to the base station 110 at the next scheduling requestopportunity. This is good.

Hence, no unnecessary scheduling request is sent in either case a) orcase b) and, thus, there is no ambiguity in the user equipment 110 as towhat a scheduling request means. In both cases a) and b), a schedulingrequest means that there is new data in the user equipment 120 that theuser equipment 110 was not previously aware of. There is still an errorcase where the scheduling request opportunity 615 is before the packetunit build 612, in which case there will be an extra scheduling requestsent and an ambiguity in the user equipment 110 as to what the SR meanssimilar to the analysis of case a) in FIG. 1, but there is a muchsmaller probability of having an SR opportunity between arrival ofsecond data and build of packet unit as in the possible error case inFIG. 6, than there is of having an SR opportunity between arrival ofsecond data and transmission of data as in FIG. 1.

FIG. 7 and FIG. 8 illustrates an analysis of the present inventionaccording to the first embodiment, where the user equipment 120 gets newdata to its buffer after a grant corresponding to the first schedulingrequest is received. This new data triggers a scheduling requesttrigger. Looking at a time line, there are then two different cases thatappears, case a) illustrated in FIG. 7 and b) illustrated in FIG. 8. Incase a), the user equipment 120 has a scheduling request opportunitybetween receiving the UL grant and transmitting the data. In case b) theuser equipment 120 has no scheduling request opportunity betweenreceiving the UL grant and transmitting the data, the next schedulingrequest opportunity comes after the transmission of the data.

In case a) and in case b) there are two respective alternatives,alternative I and alternative II. FIG. 7 depicts case a) alternative Iand case a) alternative II, and FIG. 8 depicts case b) alternative I andcase b) alternative II.

Hence FIG. 7 illustrates an analysis according to the present embodimentin the scenario when new data arrives between reception of grant andtransmission of data corresponding to the grant for case a), wherein theuser equipment 120 has a scheduling request opportunity betweenreceiving the UL grant and transmitting the data. Assume that first datahas arrived to the user equipment buffer, which corresponds to step 501in FIG. 5. This first data has triggered a buffer status report, whichcorresponds to step 502 in FIG. 5. This first data also, directly orindirectly via the buffer status report trigger, has triggered a firstscheduling request trigger for sending a scheduling request at the nextscheduling request opportunity, which corresponds to step 503 in FIG. 5.The scheduling request opportunity has occurred and the first schedulingrequest has been transmitted to the base station. The first schedulingrequest trigger is still pending. According to this embodiment, thescheduling request trigger will be cancelled when the data thattriggered the scheduling request is accounted for in a buffer statusreport to be included in a scheduled data transmission to be transmittedto the base station 110, or the user equipment 120 cancels the pendingscheduling request when the data that triggered the scheduling requestis included in a scheduled data transmission to be transmitted to thebase station, whichever occurs first.

For case a-I) assume the following steps:

Step 700 case a-I) As a response to the scheduling request sent to thebase station 110, the user equipment 120 receives from the base stationan UL grant for transmission.

Step 710 case a-I). During a time period the user equipment 120 builds apacket data unit, such as a MAC PDU, for parts or all of the first datato be transmitted in, and includes a buffer status report in the packetdata unit (unless all data can fit in but not a buffer status report).This packet data unit shall be sent to the user equipment 110 at thetransmission later on. The buffer status report accounts for the firstdata. According to the first embodiment of the present invention, thepending first scheduling request is cancelled at this point in time,which corresponds to step 504 in FIG. 5.

Step 720 case a-I). New second data arrives in the user equipmentbuffer. This second data triggers a buffer status report. This seconddata further, directly or indirectly, triggers a second schedulingrequest trigger, to send a scheduling request at the next opportunity.The second scheduling request trigger is pending, triggered by thesecond data.

Step 740 case a-I). At this point in time a scheduling requestopportunity occurs, i.e. this scheduling request opportunity occursbetween receiving the UL grant and transmitting the data according tocase a). Therefore the user equipment 120 sends a second schedulingrequest to the base station 110, since the second scheduling request ispending. This is necessary as the user equipment 120 has already builtthe packet data unit including parts or all of the first data to besent, before the second data became available in the user equipmentbuffer. The second data is thereby not accounted for in the bufferstatus report which will be sent to the base station 110 at thetransmission.

Step 750 case a-I). The user equipment 120 transmits the packet dataunit including the buffer status report, which buffer status report wastriggered by the first data (mentioned above) and which buffer statusreport accounts for the first data but not the second data. At thispoint, it is not difficult any more for the base station 110 to know howto interpret the second scheduling request sent, it corresponds to newdata not accounted for in the buffer status report received in thetransmission. Additionally, it was necessary for the user equipment 120to send the second scheduling request, since the base station 110 wouldnot have known about the second data if the second scheduling requesthad not been sent.

For case a-II) assume the following steps:

Step 700 case a-II). As a response to the first scheduling request sentto the base station, the user equipment 120 receives from the basestation 110 an UL grant for transmission.

Step 720 case a-II). New second data arrives in the user equipmentbuffer. This second data triggers a buffer status report. This seconddata further, directly or indirectly via the buffer status report,triggers a second scheduling request trigger to send a schedulingrequest at the next opportunity. In case a-II), the second data arrivesbefore building the packet data unit, wherein in case a-I) the seconddata arrived after building the packet data unit.

Step 730 case a-II). During a time period the user equipment 120 buildsa packet data unit, such as a MAC PDU, for data to be transmitted in,which data is built in the packet data unit depending on the priority ofthe data in the user equipment buffer. The user equipment includes abuffer status report in the packet data unit (unless all data can fit inbut not a buffer status report). This packet data unit shall be sent tothe base station at the transmission later on. The buffer status reportaccounts for the first and second data being built in the packed dataunit. According to the first embodiment of the present invention, thepending first and second scheduling requests are cancelled at this pointin time, which corresponds to step 504 in FIG. 5.

Step 740 case a-II). At this point in time a scheduling requestopportunity occurs, i.e. this scheduling request opportunity occursbetween receiving the UL grant and transmitting the data according tocase a). The scheduling request triggers are not pending any more.Therefore the user equipment 120 will not send any scheduling request tothe base station 110. This is good because it would have beenunnecessary to do so, since both first and second data will be accountedfor in the buffer status report sent on already allocated resources.

Step 750 case a-II). The user equipment 120 transmits data and thebuffer status report in the built packet data unit, which buffer statusreport accounts for the first data and the second data.

Hence, no unnecessary scheduling request is sent in either case a-I) orcase a-II), and thus there is no ambiguity in the base station 110 as towhat a scheduling request means. In both cases a-I) and a-II), ascheduling request means that there is new data in the user equipment120 that the base station 110 was not previously aware of. The sameerror case as described for FIG. 6 is still present, but with a muchsmaller probability of happening with the invention.

FIG. 8 illustrates an analysis according to one embodiment of thepresent invention, in the scenario when new data arrives betweenreception of grant and transmission of data corresponding to the grantfor case b) wherein the user equipment 120 has no scheduling requestopportunity between receiving the UL grant and transmitting the data,the next scheduling request opportunity occurring after the transmissionof the data. Assume that first data has arrived to the user equipmentbuffer, which corresponds to step 501 in FIG. 5. This first data hastriggered a buffer status report, which corresponds to step 502 in FIG.5. This first data also directly or indirectly via the buffer statusreport trigger, has triggered a first scheduling request trigger forsending a scheduling request at the next scheduling request opportunity,which corresponds to step 503 in FIG. 5. The scheduling requestopportunity has occurred and a first scheduling request is transmittedto the base station. The first scheduling request trigger is stillpending. According to one or more embodiments of the present invention,the scheduling request trigger will be cancelled when the data thattriggered the scheduling request is accounted for in a buffer statusreport to be included in a scheduled data transmission to be transmittedto the base station 110, or the user equipment 120 cancels the pendingscheduling request when the data that triggered the scheduling requestis included in a scheduled data transmission to be transmitted to thebase station, whichever occurs first.

For case b-I) assume the following steps:

Step 800 case b-I). As a response to the scheduling request sent to thebase station, the user equipment 120 receives from the base station anUL grant for transmission.

Step 810 case b-I). During a time period the user equipment 120 builds apacket data unit, such as a MAC PDU, for parts or all of the first datato be transmitted in, and includes a buffer status report in the packetdata unit (unless all data can fit in but not a buffer status report).This packet data unit shall be sent to the user equipment 110 at thetransmission later on. The buffer status report accounts for the firstdata. According to the first embodiment of the present invention, thepending first scheduling request is cancelled at this point in time,which corresponds to step 504 in FIG. 5.

Step 820 case b-I). New second data arrives in the user equipmentbuffer. This second data triggers a buffer status report trigger. Thissecond data further, directly or indirectly, triggers a secondscheduling request trigger, to send a scheduling request at the nextopportunity.

Step 840 case b-I). The user equipment 120 transmits the first databuilt in the packet data unit and includes the buffer status report inthe packet data unit, which buffer status report was triggered by thefirst data (mentioned above) and which buffer status report accounts forthe first data but not the second data.

Step 850 case b-I). At this point in time a scheduling requestopportunity occurs i.e. after the transmission of the data according tocase b). Since the second scheduling request trigger is pending at thispoint in time, the user equipment 120 sends a scheduling request to thebase station 110 at this point in time. This is good, since noscheduling request for the second data has been transmitted to the userequipment 110 yet. Now, there is no risk for the scheduling request forthe second data to be lost!

For case b-II) assume the following steps:

Step 800 case b-II). As a response to the scheduling request sent to thebase station, the user equipment 120 receives from the base station anUL grant for transmission.

Step 820 case b-II). New second data arrives in the user equipmentbuffer. This second data triggers a buffer status report. This seconddata further, directly or indirectly via the buffer status report,triggers a second scheduling request trigger to send a schedulingrequest at the next opportunity. In case a-II), the second data arrivesbefore building the packet data unit, whereas in case a-I the seconddata arrived after building the packet data unit.

Step 830 case b-II). During a time period the user equipment 120 buildsa packet data unit, such as a MAC PDU, for data to be transmitted in,which data is built in the packet data unit depending on the priority ofthe data in user equipments' buffers. The user equipment includes abuffer status report in the packet data unit (unless all data can fit inbut not a buffer status report). This packet data unit shall be sent tothe base station at the transmission later on. The buffer status reportaccounts for the first and second data being built in the packed dataunit. According to the first embodiment of the present invention, thepending first and second scheduling requests are cancelled at this pointin time, which corresponds to step 504 in FIG. 5.

Step 840 case b-II). The user equipment 120 transmits the data and thebuffer status report in the packet data unit, which buffer status reportaccounts for the first data and the second data.

Step 850 case b-II). At this point in time a scheduling requestopportunity occurs i.e. after the transmission of the data according tocase b). No scheduling request trigger is pending since it was cancelledin step 830. This is good in this case since first and second data arealready transmitted or accounted for in the BSR.

To perform the method steps referred to in FIG. 5 above for handling ascheduling request trigger, the user equipment 120 in one embodiment isconfigured as depicted in FIG. 9.

As mentioned above, the user equipment 120 comprises a buffer 900configured to receive data to be transmitted to the base station 110.

The user equipment 120 further comprises a generating circuit 920configured to generate a scheduling request trigger, which schedulingrequest trigger is pending until it is cancelled, and which generationis triggered directly or indirectly by the arrived data.

The user equipment 120 further comprises a cancelling circuit 930.

According to a first embodiment, the cancelling circuit 930 isconfigured to cancel the pending scheduling request trigger when thedata that triggered the generation of the scheduling request trigger isaccounted for in a buffer status report to be included in a scheduleddata transmission to be transmitted to the base station 110, or when thedata that triggered the generation of the scheduling request is includedin a scheduled data transmission to be transmitted to the base station110, whichever occurs first.

According to a second embodiment, the cancelling circuit 930 isconfigured to cancel the pending scheduling request trigger at any time,but keeps track of what data that has either been accounted for in thebuffer status report to be included in a scheduled data transmission orincluded directly in the scheduled data transmission and what data thathas not been accounted for in any of these two ways.

According to a combined first and second embodiment, the cancellingcircuit 930 is configured to cancel the pending scheduling requesttrigger when the data that triggered the generation of the schedulingrequest trigger is accounted for in a buffer status report to beincluded in a scheduled data transmission to be transmitted to the basestation 110, or when the data that triggered the generation of thescheduling request is included in a scheduled data transmission to betransmitted to the base station 110, whichever occurs first, oralternatively to cancel the pending scheduling request trigger at anytime, but keeping track of what data that has been accounted for in thebuffer status report to be included in a scheduled data transmission andwhat data that has not been accounted for.

According the second embodiment and the combined first and secondembodiment, the user equipment 120 comprises a sending circuit 940configured to, when a next scheduling request opportunity appears, senda scheduling request if and only if the buffer comprises data that hasnot yet been accounted for in any of the two ways mentioned.

According the combined first and second embodiment the sending circuit940 is configured to, when a next scheduling request opportunityappears, send a scheduling request if and only if the buffer comprisesdata that has not yet been accounted for in the buffer status report.

The present mechanism for handling a scheduling request trigger may beimplemented through one or more processors, such as a processor 950 inthe user equipment 120 depicted in FIG. 9, together with computerprogram code for performing the functions of the present invention. Theprogram code mentioned above may also be provided as a computer programproduct, for instance in the form of a data carrier carrying computerprogram code for performing the present invention when being loaded intothe user equipment 120. One such carrier may be in the form of a CD ROMdisc. It is however feasible with other data carriers such as a memorystick. The computer program code may furthermore be provided as pureprogram code on a server and downloaded to the user equipment 120.

FIG. 10 depicts one embodiment of the user equipment 120, includingprocessing circuits operatively associated with transceiver circuits(radiofrequency receiver front-end, transmit modulator/amplifier, etc.),and one or more transmit/receive antennas.

The user equipment 120 is, for example, a mobile terminal or other typeof user equipment configured for operation in a wireless communicationsystem based on the LTE standards.

In any case, the user equipment 120 is configured to implement any ofthe embodiments described herein. For example, the processing circuitsmay comprise one or more baseband processors. In at least oneembodiment, the processing circuits comprise one or moremicroprocessor-based circuits, such as a Digital Signal Processor (DSP)or other digital processor. Further, those skilled in the art willappreciate that the user equipment 120 includes one or more memorycircuits—e.g., non-volatile and volatile—for storing programinstructions, configuration and provisioning data, working data, etc.

In particular, the processing circuits within the user equipment 120include an uplink transmit buffer such as the buffer 900—which may be areserved portion of working memory—for buffering data for uplinktransmission, and an associated controller for implementing all or partof the control and processing described herein and as referred to in thetext above related to FIG. 9. That is, one or more embodiments of thecontroller such as the cancelling circuit 930, are configured to cancela pending scheduling request when the data that triggered the schedulingrequest is included in a buffer status report MAC control element or thedata that triggered the scheduling request is transmitted, whicheveroccurs first as described above. In an LTE context, the user equipment120 can be understood as being configured to cancel a pending schedulingrequest when the buffer status report that triggered the schedulingrequest is canceled.

Alternatively, the user equipment's controller can be configured viahardware, software, or some combination thereof, to track what data hasbeen included or otherwise accounted for in a buffer status report andwhat data has not. Accordingly, when a scheduling request opportunitycomes, the user equipment 120 sends a scheduling request if it has datathat has not yet been accounted for in a buffer status report (thebuffer status report does not have to have been sent; for example, it issufficient if the buffer status report is included in a MAC PDU that hasbeen assembled for transmission.)

Both embodiments 1 and 2 lead to the same behavior, the advantage ofwhich is that it is natural to cancel a pending SR when it has servedits purpose. This is only guaranteed if the pending SR is cancelled whenthe data that triggered it is already accounted for in a buffer statusreport, or the data that triggered it is transmitted. Any other solutionwill lead to ambiguities or unnecessary SRs sent and/or unnecessarygrants.

According to some embodiments, the present invention may be referred toas follows. When a scheduling request is triggered, it shall beconsidered as pending until it is cancelled. All pending schedulingrequests shall be cancelled when a MAC PDU is assembled and this PDUincludes a buffer status report which contains buffer status up to (andincluding) the last event that triggered a buffer status report, or whenthe uplink grant can accommodate all pending data available fortransmission.

When using the word “comprise” or “comprising” it shall be interpretedas non-limiting, i.e. meaning “consist at least of”. The word “built” isequal to the word “assembled” in this text.

The present invention is not limited to the above described preferredembodiments. Various alternatives, modifications and equivalents may beused. Therefore, the above embodiments should not be taken as limitingthe scope of the invention, which is defined by the claims and theirlegal equivalents.

1. A method in a user equipment for requesting that a base stationschedule the user equipment for an uplink data transmission to the basestation, the user equipment comprising a buffer, the method comprising:receiving data into said buffer that is to be transmitted to the basestation via a scheduled uplink data transmission; and sending ascheduling request to the base station when a next scheduling requestopportunity occurs, if and only if the buffer contains data that hasneither been accounted for in a buffer status report, which reports thesize of said buffer to the base station, or included directly in ascheduled uplink data transmission.
 2. The method of claim 1, whereinsending a scheduling request to the base station when a next schedulingrequest opportunity occurs, if and only if the buffer contains data thathas neither been accounted for in a buffer status report or includeddirectly in a scheduled uplink data transmission comprises: generating ascheduling request trigger directly, or indirectly, responsive to thearrival of said data into said buffer, the scheduling request triggerconfigured to trigger the sending of a scheduling request to the basestation if the trigger is pending at the next scheduling requestopportunity and to remain pending until it is cancelled, and cancellingthe pending scheduling request trigger when said data is accounted forin a buffer status report, or when said data is included directly in ascheduled uplink data transmission, whichever occurs first; and sendinga scheduling request to the base station when a next scheduling requestopportunity occurs, if and only if a scheduling request trigger ispending at that next scheduling request opportunity.
 3. The method ofclaim 2, wherein generating a scheduling request trigger directly, orindirectly, responsive to the arrival of said data into said buffercomprises: generating a buffer status report trigger responsive to thearrival of said data into said buffer, the buffer status report triggerconfigured to trigger the generation of a buffer status report; andgenerating the scheduling request trigger indirectly responsive to thearrival of said data, by generating the scheduling request triggerresponsive to the generation of said buffer status report trigger. 4.The method of claim 3, wherein cancelling the pending scheduling requesttrigger comprises cancelling the buffer status report trigger, which inturn triggers the canceling of the scheduling request trigger.
 5. Themethod of claim 1, wherein sending a scheduling request to the basestation when a next scheduling request opportunity occurs, if and onlyif the buffer contains data that has neither been accounted for in abuffer status report or included directly in a scheduled uplink datatransmission comprises: tracking what data in said buffer has beenaccounted for in a buffer status report and what data in said buffer hasbeen included directly in a scheduled uplink data transmission, andtracking what data has not been accounted for in said buffer statusreport or included directly in said scheduled uplink data transmission.6. The method of claim 1, wherein sending a scheduling request to thebase station if and only if the buffer contains data that has not beenincluded directly in a scheduled uplink data transmission comprisessending a scheduling request to the base station if and only if thebuffer contains data that has not been included directly in a packetdata unit that is scheduled to be transmitted to the base station.
 7. Auser equipment configured to request that a base station schedule theuser equipment for an uplink data transmission to the base station, theuser equipment comprising a buffer, the user equipment comprising: abuffer configured to receive data to be transmitted to a base stationvia a scheduled uplink transmission; and a sending circuit configured tosend a scheduling request to the base station when a next schedulingrequest opportunity occurs if and only if the buffer contains data thathas neither been accounted for in a buffer status report, which reportsthe size of said buffer to the base station, or included directly in ascheduled uplink data transmission.
 8. The user equipment of claim 7:further comprising a generating circuit configured to generate ascheduling request trigger directly, or indirectly, responsive to thearrival of said data into said buffer, the scheduling request triggerconfigured to trigger the sending of a scheduling request to the basestation if the trigger is pending at the next scheduling requestopportunity and to remain pending until it is cancelled, and furthercomprising a cancelling circuit configured to cancel the pendingscheduling request trigger when said data is accounted for in a bufferstatus report, or when said data is included in a scheduled uplink datatransmission, whichever occurs first; and wherein the sending circuit isconfigured to send a scheduling request to the base station when a nextscheduling request opportunity occurs, if and only if a schedulingrequest trigger is pending at that next scheduling request opportunity9. The user equipment of claim 8, wherein the generation circuit isconfigured to generate a scheduling request trigger indirectlyresponsive to the arrival of said data into said buffer, by: generatinga buffer status report trigger responsive to the arrival of said datainto said buffer, the buffer status report trigger configured to triggerthe generation of a buffer status report; and generating the schedulingrequest trigger responsive to the generation of said buffer statusreport trigger.
 10. The user equipment of claim 9, wherein thecancellation circuit is configured to cancel the pending schedulingrequest trigger by cancelling the buffer status report trigger, which inturn triggers the canceling of the scheduling request trigger.
 11. Theuser equipment of claim 7: further comprising a cancellation circuitconfigured to track what data in said buffer has been accounted for in abuffer status report and what data in said buffer has been includeddirectly in a scheduled uplink data transmission, and to track what datahas not been accounted for in said buffer status report or includeddirectly in said scheduled uplink data transmission; and wherein thesending circuit is configured to send a scheduling request to the basestation when a next scheduling request opportunity occurs, if and onlyif the buffer contains data that has neither been accounted for in abuffer status report or included directly in a scheduled uplink datatransmission, as indicated by said tracking in said cancellationcircuit.
 12. The user equipment of claim 7, wherein the sending circuitis configured to send a scheduling request to the base station when anext scheduling request opportunity occurs if and only if the buffercomprises data that has neither been accounted for in a buffer statusreport, which reports the size of said buffer to the base station, orincluded directly in a packet data unit that is scheduled to betransmitted to the base station